Two-way plow



June 5, 1951 w. N. OLSON ETAL TWO-WAY PLOW Filed July 2, 1945 3 Sheets-Sheet 1 zwzzzzzzzwazswz dig/Zea? Gfjdazs.

3 Sheets-Sheet 2 I (J dre 2a? C. ,IUCZ/"ZS,

@ PM P TWO-WAY PLOW W. N. OLSON ETAL June 5, 1951 Filed July 2, 1945 June 5, 1951 w N, OLSON ETAL 2,555,555

TWO-WAY PLOW Filed July 2, 1945 3 Sheets-Sheet 3 4e g6 I 4 n 96 o 22 69 ll z 'I J J Patented June 5, 1951 TWO-WAY PLOW William N. Olson and Arthur G. Evans, Canton,

Ill., assignors'to International Harvester Company, a corporation of new Jersey Application July 2, 1945, Serial No. 602,762

This invention relates to agricultural implements and particularly to those adapted to be mounted upon a tractor or the like to be carried thereby. More specifically, the invention con cerns a tractor-mounted two-way plow.

An object of the invention is to provide a novel two-way plow of improved construction.

' Another object is to provide a tractor-mounted agricultural implement having improved means for controlling the operation thereof.

Still another object is to provide in a tractormounted agricultural implement novel means for leveling the earth-working tool when one wheel of the tractor'is traveling in a furrow.

Another object is to provide, in a tractormounted two-way plow, lift means on the tractor for vertically moving the entire implement to and from transport position, and separate means for alternately operating the individual plow units.

Other objects and advantages will become clear from the following detailed description when read in conjunction with the accompanying drawings, whereini Figure ,I'is a viewinside elevation of the rear portion of a tractor with one wheel removed and showing attached thereto a two-way plow embodying-the features of the present invention;

Figure 2 is a plan view of the structure shown in Figure I;

Figure 3 is a rear elevation of the structure shown in Figures 1 and 2 with parts removed for clarity and showing the right-hand plow bottom in operating position;

Figure 4 shows an enlarged detail of the lifting structure by which the alternately operable plow units are moved to and from operating position;

Figure 5 is a plan view of the structure shown in Figure 4 prior to the lifting operation;

Figure 6 is a detail of a portion of the structure shown in Figure 5; and

Figure? is an alternate arrangement of power mechanism on the tractor, wherein two separate rock-shafts are utilized and rocked by a separate power mechanism.

Referring to the drawings, it will be noted, particularly well in Figure 2, that the implement of the present invention is mounted upon a tractor having a laterally offset longitudinally extending body ID, a rear axle housing I l, a transverse rear axle l2 and depending stub axle housings l3 and I 4 upon which are mounted respectively rear drive wheels [5 and i6. The tractor is provided with an operators seat I! and a steering mechanism 18.

Secured to the rear axle housing and at opposite 8 Claims. (01'. 97-29) sidesthereof are conventional fenders i9 and to whichare secured bearing members 2| and 22 serving to rotatably support the ends of a transverse shaft 23. Secured to the shaft 23 at the right side thereof is a rearwardly extending arm 2!, and mounted upon a sleeve 25 rotatable upon the shaft 23 at the left side thereof is another arm 26 parallel to arm 24. Likewise fastened to the shaft 23 adjacent the sleeve 25 is an upwardly extending arm 21 provided with :an ear 28 having an opening therein to receive the threaded end of a crank 29 seated in a correspondingly threaded sleeve member 30 having its lower end bifurcated and pivoted upon the arm 26, for adjustment of the arm 26 vertically. A forwardlypro jecting lug 3| has attached thereto a forwardly extending lifting member 32 comprising a sleeve 33 pivotally attached at its rear end to thelug 3i and adapted to receive therein a rod 34, the rear end of which is slidable in the sleeve-3'3, and in which is provided a radially projecting pin 35 which extends outwardly through a slot 36in the sleeve 33, so that a limited amount of lost motion is provided between the rod 34 and the sleeve 33. The forward end of rod 3 is pivotally connected to a rock-arm?! mounted upon the left-hand end of a transverse rock-shaft 38 extending from one side of the tractor body to the other and having secured to the righthand end thereof, on the other side of the tractor body, a rock-arm 39. .This rock-shaft may be rocked about its axis by any suitable means, for example,'by a double acting hydraulic cylinder. indicated at 40, and deriving power from the tractor motor in a manner not shown. It should now be clear that rocking in a fore and aft di:- rection of the arm 31, acting through the member 32, will also rock the shaft 23 to which are secured the arms 24 and 27.

As best shown in Figure 3,'there are pivotally secured to the rearwardly extending ends of arms 2 and 26 a pair of laterally spaced depending lifting links 4i. lhese links include a sleeve member 42'and a shaft member 43. Openings are provided in the sleeve 42 and shaft 43 adapted to register to receive a pin 44, a number of openings being provided to permit adjusting of the links 4 I. The lower end of left-hand sleeve member 42 and the upper end of right-hand member 12 are connected by a similarly telescoping link 45 which includes a sleeve 46 and a shaft 41. The

sleeve 46 is provided with alslot 46; adapted to receive a pin 48 passed through openingsin the shaft 4'! to permit limited telescoping movement of the link 45, so that the links 4| will be permitted T N-T OFFICE V Y-shaped frame indicated at a certain amount of lateral swinging movement about their pivotal connections to the arms 24 and 26. The arms 24 and 26 and the links 4| function as lifting mechanism for the two-way plow of the present invention in order to move it to and from transport position on the tractor, separate means being provided, as will hereinafter become clear, for moving the alternately operable plow units into and out of ground working position.

In Figures 1, 2 and 3 of the drawings, the implement is shown with the right-hand plow bottom in earth-working position and with the lefthand plow bottom raised to inoperative position. As will be noted in Figure 3, when the right-hand plow bottom is in working position, the righthand tractor wheel I6 is traveling in the furrow previously made and is at a lower level than the left-hand tractor wheel l5 which is traveling upon the surface of the unplowed ground. Of course, when the direction of plowing is reversed, the right-hand plow bottom is raised to an inoperative position, the left-hand tractor wheel travels in the furrow, and the left-hand plow bottom is placed in operating position.

The two-way plow of the present invention includes a transverse tool-bar 49 of generally round cross-section to which are secured, adjacent opposite ends thereof, the ends of rearwardly diverging arms 59 forming a part of a generally The arms 56 converge forwardly and are secured to a longitudinally extending tubular member 52, the rear end of which is braced by a cross-piece 53 extending between the arms 59. The internal structure of-the tubular or stem member 52 forms no part member 54 slidable within the tubular member 52 against the action of a spring, not shown. The member 54 is pivotally secured by a pin 55 to a pair of vertically spaced plates 56 spaced by rollers 51 triangularly arranged to embrace opposite sides of the transverse portion 59 of a drawbar 59. It will be noted in Figure 2 that the rollers 51 are so arranged that two of them engage the rear edge of the drawbar 59 and one of them engages the forward edge thereof. The space between the plates 56 is such that movement of the plate members along the transverse portion 58 of the drawbar is accommodated. The drawbar 59 is U-shaped and the laterally spaced arms 66 thereof are pivotally connected by bolts 5| to brackets 62 secured to the depending axle housings I3 and M. The drawbar 59 thus is capable of vertical swinging movement about the pivots 6|.

To the upper plate 56 is pivotally secured the lower end of a telescoping link 63 including a sleeve member 64 pivotally attached to a lug 64 secured to the upper plate 56. A shaft 65 is provided with a number of openings 66 to receive a pin 67 passed through the sleeve 64 for adjusting the effective length of the link 63. The upper end of shaft member 65 is connected to the rockarm 39 secured to the right-hand end of rockshaft 38, through the intermediary of an extension member 68 bolted to the arm 39. Member 68 has a short portion 69 extending forwardly from the arm 39 to which the shaft 65 is pivotally attached. Member 68 also is provided with a longer rearwardly extending portion 19. It should now be clear that the drawbar 59, and

therefore the forward end of frame member 5|,

may be moved up and down by rocking the arm 39. It should also be understood that the connection of sleeve 64 to the lug 64 is sufficiently loose to accommodate the lateral movementof the hitch frame 5| along the drawbar 59.

The rearwardly diverging ends of arms 59 of frame member 5| are secured to the transverse tool-bar 49 by clamps Pivotally connected to'transverse tool-bar 49 for vertical swinging movement with respect thereto are laterally spaced plow units if and i3 including, respectively, tool-beams l4 and 15 which curve downwardly at their rear ends and are provided with plow bottoms l5 and 11. These plow units are substantial duplicates and, generally, a description of one will suffice for both. As clearly shown in Figure 3, beam 74 is provided at its forward end with a bearing portion I8 mounted upon a cylindrical portion of the toolbar 49. Likewise secured to the forward end of the beam is a rectangular box-like member 19 which extends laterally from the beam and is provided with a bearing portion 86 also rotatable upon a cylindrical portion of thebar 49. A side wall 6! of member 79 opposite the beam 14 is provided with a slot 32 in which is adjustably mounted a bolt 83 having secured to the inner end thereof a'member 84 threaded'to receive a bolt 85 extending through an opening in the rear wall of the member 19 and held against relative displacement therein. By turning the bolt 85 in the member 84, the bolt 83 can be adjusted in the slot 62, the purpose of which will hereinafter become clear.

Also mounted upon the bolt 83 is an arcuate link 96 which curves upwardly and forwardly and is provided at its end with a pin 97 which also pivotally mounts the lower end of the shaft member 43 of link 4|. Likewise pivoted upon the pin 8'! is one end of a link 88, the other end of which is pivotally connected to the inwardly projecting end 89 of an upwardly extending arm 99' having a socket portion shaped to fit the squared outer ends of the tool-bar 49 and secured thereto by bolts 9|. T 7

Since the point of connection of the arcuate link 86 to the bolt 33 is spaced'f rom the pivot axis of the beam 14 upon the tool-bar, it should be clear that when the beam is raised from the ground to the position shown in the drawings, the

link 86 will urge the link 88 upwardly about its pivot upon the arm 99. Thus the distance between the point of connection of link 4| with arm 26 and the pivot axis of tool-bar 49 will be increased. The purpose of this increase in the effective len th of the linkage including links 4| and 86 on the side of the raised plow unit is to automatically level the plow bottom which is in working position. Thus the tool bar 49 i permitted to remain parallel with the ground at all times so that the plow bottom 1'! will be in proper relation to the ground through which it passes. The mechanism just described by which the beam 14 is connected to the tool-bar and to the lifting linkage is, of course, duplicated with the plow unit 13.

In order to equalize the plow units and provide for one of them to remain in raised position during operation of the other, a mechanism is provided including an equalizer bar 92 which extends transversely of the implement and has secured to the center thereof a pin 93 rotatably mounted in a bearing 94 secured to the forward end of a bar 94 The equalizer bar 92 thus has'pivotal movement about 'a vertical axis. Each end of the equalizer bar 92 is connected by a link 95 with a lug 96 depending from the member 19 of the respective plow units. Thus upon vertical swinging movement of the plow units, one into raised position and the other into ground working position, the lugs 96 of the respective plow units are rocked in opposite directions. In other words, upon raising the plow unit 12 to inoperative position, as indicated in the drawings, lug 90 of that plow unit swings rearwardly and causes the equalizer bar to assume the position shown in Figure 2. Simultaneously, the downward movement of the right-hand plow unit I3 to working position causes the lug 90 on that unit to move forwardly to swing the equalizer bar about its pivot. The unit in inoperative position is held there by the engagement of latch 99 with block 98 carried by main frame bar 94 The bar 94* extends rearwardly and at its intermediate portion is provided with a bearing portion 91 mounted upon a cylindrical center portion of the tool-bar 49, as indicated in Figures 2 and 5. The end of bar 94 projecting rearwardly from the tool-bar 49 has secured to the lower portion thereof, as by welding, a transverse wedge-shaped block 98 shown in detail in Figure 6. This block serves to clamp the operating plOW unit in position by a mechanism including a latch 99 pivoted at I09 to the plow beam 14, as shown in Figure 4. When the plow unit is in operating position, the hook portion I9I f latch 99 engages the under-surface of the block 98 to hold the plow unit against upward movement. The latch 99 is biased to engaged position with block 98 by a spring I02 connected to the plow beam and the latch.

Alternate raising and lowering of the plow bottoms to and from working position is accomplished by a lifting mechanism including a pair of laterally spaced straps I03, the rear ends of which are pivotall mounted upon a pin I04 seated in the laterally spaced arms of a rockable member I 05 which is pivotally mounted upon the tool-bar 49 centrally thereof for rocking movement in a forward and rearward direction. Arm I05 is provided with an extension I06, having secured between the laterally spaced portions thereof a U-shaped bracket I01, having openings in the bent portions thereof to receive the shank I08 of a crank I09. The forward end of the shank portion I08 is provided with an opening to receive a pin H0 which extends through the laterally spaced portions of the arm 05 and is provided therebetween with springs III, one on each side of the shank I08. The opening in the end of shank I 08, which receives the pin H0, is considerably larger than the pin to allow angular movement of the crank I09 with respect to the pin IIO against the action of the springs III. While the springs I II tend to hold the crank I09 in a centered position, as indicated in Figure 5, a certain amount of lateral play of the crank is permitted, the springs tending to return the crank to its normal centered position.

As shown in the drawings, particularly Figures 1, 3 and 4, each of the latches 99 pivoted on the beams 14 and I5 is provided with a lug II2 having its under-surface angled outwardly and downwardly as indicated in Figure 3. When the plow unit is in operating position, the lug II2 lies directly over a rearwardly extending portion I I3 of crank I09 in the relationship shown in Figure 3, so that upon upward movement of the crank I09, due to forward rocking of the arm I05 about its pivot on the bar 49, th portion II3 of the crank will engage the under surface of the lug I [I2 near its outer end. In the centered position of the crank I09, the shank portion I08 thereof is seated in an arcuate notch in a member secured to the upper surface of the member 94*. Upon rocking arm I05 the crank will ride upwardly and outwardly along the lower inclined surface of the lug and will be deflected laterally to hook itself securely under the lug I I2. The forward ends of straps I03 are spaced by a pin I03 to which is connected one end of a flexible member I It which extends forwardly and upwardly and engages near its intermediate portion a roller I I5 mounted upon a pin H0 in the ends of brackets II'I secured to the tractor by bolts H8. Brackets I I! are further braced by a strap II9 secured to the side of the tractor body. The forwardly extending end of flexible member H4 is pivotally secured to the rearwardly extending arm 10 of the extension 68 on rock-arm 39. Upon rocking of the rock-shaft 38 and forward movement of arm 39, the flexible member I I4 is brought forward to pivot the arm I05 forwardly about its connection to the transverse tool-bar d9, thus engaging the crank I09 with the lug II2 of the plow unit in operating position and raising it to inoperative position. The direction of movement of rockarm 39 is then reversed and the arm I05 permitted to pivot in the opposite direction to return the crank I99 to an operative position with respect to the plow unit then in working position. Slack is then introduced into the flexible member II l, as indicated in Figure 1. Limited movement of the rock-arm 39 with raising and lowering of the draw-bar 59 and the plow hitch point may now be effected to adjust the depth of operation of the plow without actuating th mechanism which raises the individual units to inoperative position.

As pointed out before, each of the latches 09 on the plow units 12 and I3 is provided with a latch lug I I2 so that each is alternately engageable with the crank I09. Upon return of the crank to operating position, after lifting the inoperative plow bottom, the rearwardly extending portion H3 of the crank is deflected laterally by the downwardly curved upper portion of the lug H2 and is brought back to a centered position therebelow through the action of the springs I I I.

The crank I09 is urged back to operative position with respect to the working plow bottom by a spring I20, the forward end of which is secured to the pin I03 and the rear end of which is anchored in a manner that will hereinafter appear. Secured to the bearing 94 forwardly thereof is another bearing IZI set at an angle to the axis of bearing 94. The rear end of spring I20 is anchored to the bearing !2I. Adjustably mounted in the bearing I2I is a generally vertically extending standard I22 secured against rotation preferably by a set-screw or the like, not shown. To the lower portion of the standard I22 is secured a bracket I23 which comprises laterally spaced elements 124 extending rearwardly and having bearings at the end thereof to support a coulter I25.

As will be noted in Figures 1 and 3, the coulter I25 rides directly in front of the operating plow bottom and is spaced slightly from the landward side thereof. The function of a coulter, as is well known in the art, is to slice the ground in advance of the plow bottom and open a path therefor. Due to the close proximity of the plow units 12 and T3, the coulter is so arranged that it is in position to function for either plow bottom. It

isthus possible. to eliminate a great deal ,of the weight that would be added to the implement by the use of a second coulter, and likewiseiin a compact implement, such as that shown and described, wherein space is at a premium, it is important .to reduce tov aminimum the number of parts which might interfere with the efficient operation .of the implement. In some instances it is desirable to-utilize a gauge'w-heel and such a wheel may be supported by the same standard that supports the coulter 125; for eXarnple the combination gauge'wheel and coulterlunit shown and? described in: United States Patent No. 2,420,551, may be employed.

.As pointed out before, lifting of the entire implement to transport position on the tractor is accomplished by rocking the shaft 38 to move the arm 31 forwardly. Let us assume that the implement is in the position shown in Figure 1 and that it is desired to raise it to its transport position. Arms 31 and 39 are rocked forwardly. Due to the arc of movement of arm 39 from the position indicated in Figure 1, and link 63 connecting the arm to the draw-bar 59, the drawbar and therefore the front end of the frame member 5| is raised. Pin 35 abuts the forward end of slot 36 and the entire implement is lifted.

.By virtue of the connection of opposite ends of equalizer bar 92 to lugs 96 of the respective plow units it is, of course, impossible for both of the plow units to be raised to inoperative position by power. A glance at Figure 2 will show that the plow units are balanced and that one of them cannot be lifted without causing lowering of the other. It is customary, therefore, after the implement has been lifted to transport position from an operating position such as that shown in Figure 1, to swing the lowered plow unit 13 upwardly by hand to a position alongside the left hand unit 12. This, of course, necessitates manually releasing the latch 99, and in order to raise the unit 13;"unit 12 must be lowered somewhat, so that in their transport position the two units occupy a position approximately midway between the ground working and inoperative positions illustrated in Figure 1. Thus it should be clear that While the implement as a whole may be raised and lowered bodily by the arms 24 and 25 and theJifting linkage comprising links Al and 86, the inoperative position of each of the units '12 and 13 involves an additional movement thereof about-their pivotal connections to the tool-bar 49, and' this is accomplished by the connection of rock-arm 39 through member I I4, straps I03 and crank I09 alternately engaging one of the latches The operation of the individual plow units to alternately move them between ground working and inoperative positions is accomplished by the forward rocking of arm 39 on the right-hand side of the tractor, which consequently actuates the crank I89 to lift the working plow bottom. This rocking of the arm 39 likewise raises the hitch point of the plow by virtue of the member 63 connecting the rock-arm with the lug 64 thus tilting the point of the plow bottom upwardly and permitting it to ride out of the ground. Therefore the raising of the individual plow units by movement of the arm 39 necessarily involves a certain amount of lifting movement of the entire implement through the intermediary of rock-arm 31 and lifting member 32.

in the modification shown in Figure 7, separate rock-shafts 26 and I21 may be utilized in place of the single rock-shaft 38. In such case, .the rock-shafts 26 and I2! are rocked respectively by separate hydraulic cylinders l2;8 and. l 29. ered from the tractor motor and independently controlled in any suitable manner, not shown, to provide for independentrocking of the shafts I26 and I21. In this form of invention, the rock-arm 39 may be actuated to alternately operate the plow units and regulate thedepth of operation thereof without involving lifting of the implement as a whole. Likewise, if desired, independent'means may be provided for laterally adjusting the hitch point. Such control is of importance in side hill plowing where it is often necessary to compensate for downhill shifting of the operating plow bottom.

The two units of a two-way plow, of course, occupy different draft relations with respect to the draft vehicle, and when alternate plow bottoms are placed in operation the hitch point of the implement must be laterally moved so that the working plow bottom may be in correct plowing position with respect to the vehicle. It is therefore necessary to provide means for adjusting the point of connection of the implement to'the tractor. As previously noted, the hitch frame 5! is connected to the draw-bar 59 by means permitting lateral movement of the hitch frame to a position in alinement with the plow unit which is in operating position. In

order to accomplish this shifting of the hitch point, a bracket I38 is secured to the draw-bar,

and pivoted thereupon is a bell-crank having arms 53! and E32. Arm I3! is connected by a rod I 33 with the equalizing bar 92 and on the right-hand end thereof. The other arm I32 of the beihcrank is connected by a rod I34 with one of the plates 5%. Upon forward movement of the rock-arm 39 to move the plow unit '52 from an operating position to the raised position, indicated in the drawings, the link 95 connecting the plow unit to the equalizer bar 92 on the lefthand side is pushed rearwardly. The forward pivoting of the right-hand side of the equalizer bar 92, acting through connecting rod I33, rocks the bell-crank arms l3! and E32 about their pivotal connection with the bracket 36 to move the hitch frame and the point of connection thereof to the draw-bar toward the right to properly line the hitch point with the plow unit 13 which is in operating position. This forward movement of the right-hand side of equalizer bar 92 likewise rocks the lug 96 forwardly and moves the plow unit '73 into operating position.

It should now be clear that a novel tractormounted two-way plow has been described embodying many useful and novel features. While the invention has been described in its preferred embodiment, however, it should be understood that modifications be made therein without departing from the spirit of the invention or the scope of the appended claims.

What is claimed is:

1. In combination with a tractor having a hitch point, an agricultural implement connected to the tractor to be at least partly supported thereby, comprising a longitudinally extending tool-carrying structure connected at its forward end to the tractor at said hitch point for vertical swinging movement about a transverse axis, means for laterally adjusting the forward end of said tool-carrying structure at said hitch point, and means accommodating said lateral adjustment for simultaneously adjusting the for- These cylinders'may likewise be pow-V ward end of said tool-carrying structure generally vertically.

2. The combination with a tractor having a movable hitch point, of a two-way plow including a frame, means connecting the frame to the tractor at said hitch point for lateral movement with respect thereto to change the location of the hitch point, a pair of laterally spaced plow units alternately movable between groundworking and inoperative positions, power means on the tractor, releasable means connecting said power means to the unit in ground-working posi-- tion for raising said unit to inoperative position, and means operatively connecting the latter unit to said frame adjacent said hitch point to laterally move said hitch point in response to the raising of said unit to inoperative position.

3. The combination with a tractor having a movable hitch point, of a two-way plow including a frame, means connecting the frame to the tractor at said hitch point for lateral movement with respect thereto to change the location of the hitch point, a pair of laterally spaced plow units alternately movable between groundworking and inoperative positions, power means on the tractor, releasable means connecting said power means to the unit in ground-working position for raising said unit to inoperative posi tion, and means responsive to lifting of said. latter unit for moving said hitch point laterally and for simultaneously lowering the inoperative unit to ground-working position.

4. In combination with a tractor having a movable hitch point and power-lift mechanism thereon, a two-way plow pivotally connected to the tractor in draft receiving relation thereto at said hitch point to be supported thereby for vertical swinging movement about a transverse axis, comprising laterally spaced plow units adapted for alternate operation, a pair of rock arms on the tractor, lift means connecting one of said arms to said plow for raising said units simultaneously to transport position, means operatively connecting the other of said arms to said units for placing the plow units in position for alternate operation thereof, means connecting said other arm to the plow adjacent said hitch point for vertically adjusting the latter simultaneously with placing the plow units in position for alternate operation, and power means for rocking said rock arms.

.5. In a tractor-mounted agricultural implement, power means on the tractor, an implement frame, a pair of vertically extending laterally spaced lifting link structures connecting the power means to the frame for moving the implement into and out of operating position, one said link structure including relatively movable parts automatically operable durin movement of the implement to increase the effective length of said link structure, whereby to level the implement.

6. In a tractor-mounted two-way plow, power lift means on the tractor, means serving as a plow frame connected to the tractor for generally vertical movement with respect thereto, laterally spaced plowing units carried by said frame and alternately movable with respect thereto to and from operating position, a pair of laterally spaced lifting link structures connecting the power-lift means to said frame to raise and lower the latter with respect to the tractor, and means for increasing the effective length of one said link structure in response to the movement of one of said units to inoperative position.

7. In a tractor-mounted two-way plow, power lift means on the tractor, means serving as a plow frame connected to the tractor for generally vertical movement with respect thereto, laterally spaced plowing units carried by said frame and alternately movable with respect thereto to and from operating position, a pair of laterally spaced lifting link structures connecting the power lift means to said frame to raise and lower the latter with respect to the tractor, means for increasing the effective length of one said link structure in response to the movement of one of said units to inoperative position, and means for adjusting the extent of said increase.

8. In combination with a tractor having a movable hitch point and power-lift mechanism thereon, a two-way plow pivotally connected to the tractor in draft receiving relation thereto at said hitch point to be supported thereby for vertical swinging movement about a transverse axis, comprising laterally spaced plow units adapted for alternate operation, a rock shaft on the tractor, a pair of rock arms on said shaft, lift means connecting one of said arms to said plow for raising said units simultaneously to transport position, means operatively connecting the other of said arms to said units for placing the plow units in position for alternate operation thereof, means connecting said other arm to the plow adjacent said hitch point for vertically adjusting the latter simultaneously with placing the plow units in position for alternate operation, and power means for rocking said rock arms.

WILLIAM N. OLSON. ARTHUR G. EVANS.

REFERENCES CITED The following references are of record in the file of, this patent:

UNITED STATES PATENTS Number Name Date 441,891 Pehrson Dec. 2, 1890 1,187,859 Parker June 30, 1916 1,363,755 Reynolds Dec. 28, 1920 1,381,662 Reynolds June 14, 1921 1,446,826 Brown Feb. 27, 1923 1,902,845 Graham et al Mar. 28, 1933 2,204,487 Glorficld June 11, 1940 2,302,502 Morkoski et a1 Nov. 17, 1942 2,306,814 Knapp Dec. 29, 1942 2,312,616 Altgelt Mar. 2, 1943 2,344,474 Tanke Mar. 14, 1944 2,358,964 Nofisinger Sept. 26, 1944 2,395,322 Evans Feb. 19, 1946 2,416,207 Olson Feb. 18, 1947 2,420,530 Evans May 13, 1947 2,424,192 Rogers et a1 July 15, 1947 2,437,879 Ferguson Mar. 16, 1948 

